<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <div id="app">
    x: {{ x}}
    y: {{ y}}
  </div>
  <script type="module">
    import { createApp, reactive, onMounted, onUnmounted, toRefs } from './node_modules/vue/dist/vue.esm-browser.js'
    function useMousePosition() {
      const position = reactive({
        x: 0,
        y: 0
      })
      const update = e => {
        position.x = e.pageX
        position.y = e.pageY
      }

      onMounted(() => {
        window.addEventListener('mousemove', update)
      })
      onUnmounted(() => {
        window.removeEventListener('mousemove', update)
      })
      return toRefs(position)
    }

    const app = createApp({
      setup() {
        // 第一个参数 props
        // 第二个参数 context：attrs、emit、slots
        const {x, y} = useMousePosition()
        return {
          x,
          y
        }
      }
    })
    console.log(app)
    app.mount('#app')
  </script>
</body>

</html>